Initial commit of IFS - a inode-namespaced FFS. Here is a short

description:

How it works:
--

Basically ifs is a copy of ffs, overriding some vfs/vnops. (Yes, hack.)
I didn't see the need in duplicating all of sys/ufs/ffs to get this
off the ground.

File creation is done through a special file - 'newfile' . When newfile
is called, the system allocates and returns an inode. Note that newfile
is done in a cloning fashion:

fd = open("newfile", O_CREAT|O_RDWR, 0644);
fstat(fd, &st);

printf("new file is %d\n", (int)st.st_ino);

Once you have created a file, you can open() and unlink() it by its returned
inode number retrieved from the stat call, ie:

fd = open("5", O_RDWR);

The creation permissions depend entirely if you have write access to the
root directory of the filesystem.

To get the list of currently allocated inodes, VOP_READDIR has been added
which returns a directory listing of those currently allocated.

--

What this entails:

* patching conf/files and conf/options to include IFS as a new compile
  option (and since ifs depends upon FFS, include the FFS routines)

* An entry in i386/conf/NOTES indicating IFS exists and where to go for
  an explanation

* Unstaticize a couple of routines in src/sys/ufs/ffs/ which the IFS
  routines require (ffs_mount() and ffs_reload())

* a new bunch of routines in src/sys/ufs/ifs/ which implement the IFS
  routines. IFS replaces some of the vfsops, and a handful of vnops -
  most notably are VFS_VGET(), VOP_LOOKUP(), VOP_UNLINK() and VOP_READDIR().
  Any other directory operation is marked as invalid.

What this results in:

* an IFS partition's create permissions are controlled by the perm/ownership of
  the root mount point, just like a normal directory

* Each inode has perm and ownership too

* IFS does *NOT* mean an FFS partition can be opened per inode. This is a
  completely seperate filesystem here

* Softupdates doesn't work with IFS, and really I don't think it needs it.
  Besides, fsck's are FAST. (Try it :-)

* Inodes 0 and 1 aren't allocatable because they are special (dump/swap IIRC).
  Inode 2 isn't allocatable since UFS/FFS locks all inodes in the system against
  this particular inode, and unravelling THAT code isn't trivial. Therefore,
  useful inodes start at 3.

Enjoy, and feedback is definitely appreciated!

1 files changed, 2 insertions, 2 deletions

diff --git a/sys/ufs/ffs/ffs_vnops.c b/sys/ufs/ffs/ffs_vnops.c
index b9a83f5..bc26dd4 100644
--- a/sys/ufs/ffs/ffs_vnops.c
+++ b/sys/ufs/ffs/ffs_vnops.c
@@ -65,7 +65,7 @@
 #include <ufs/ffs/fs.h>
 #include <ufs/ffs/ffs_extern.h>
 
-static int	ffs_fsync __P((struct vop_fsync_args *));
+int	ffs_fsync __P((struct vop_fsync_args *));
 static int	ffs_getpages __P((struct vop_getpages_args *));
 static int	ffs_putpages __P((struct vop_putpages_args *));
 static int	ffs_read __P((struct vop_read_args *));
@@ -128,7 +128,7 @@ VNODEOP_SET(ffs_fifoop_opv_desc);
  * Synch an open file.
  */
 /* ARGSUSED */
-static int
+int
 ffs_fsync(ap)
 	struct vop_fsync_args /* {
 		struct vnode *a_vp;